Operation modes

The product has two operation modes:

  • Normal operation – unencrypted mode

  • Normal operation – encrypted mode

Normal operation – unencrypted mode

In normal operation unencrypted mode, the product will send unencrypted messages every 3rd minute. This mode is normally used when the master or AMR/AMM system does not handle AES encryption or if the AES key is unknown to the system.

The link layer address is composed of the manufacturer code "ELV", the 8-digit unique ID (serial number), a version number and a device type code "Room sensor" (0x1B). The telegram has a "short application header" (CI code = 0x7A) consisting of an ACC byte, a STATUS byte and a CONFIG word. No encryption key is needed to receive the unencrypted telegrams.

Normal operation – encrypted mode

Encrypted mode is similar to unencrypted mode, but adds an encryption on the application layer using encryption mode 5 (AES128 CBC mode with dynamic initialization vector according to the standard EN13757-4:2013).

Unencrypted and encrypted modes both use exactly the same link layer address and short application header except that the header CONFIG word is different due to the encryption. The product's unique 128-bit encryption key must be known to decrypt the encrypted telegrams.

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